Ulrich Bonnell Phillips (November 4, 1877 – January 21, 1934) was an American historian who largely defined the field of the social and economic studies of the history of the Antebellum South and slavery in the U.S. Phillips concentrated on the large plantations that dominated the Southern economy, and he did not investigate the numerous small farmers who held few slaves. He concluded that plantation slavery produced great wealth, but was a dead end, economically, that left the South bypassed by the industrial revolution underway in the North.